1. FIELD OF THE INVENTION
This invention relates to aluminum extruded panels for use in forming the wall of a swimming pool wherein the panels themselves are capable of withstanding the hoop stresses encountered along the entire joint between adjacent panels.
2. DESCRIPTION OF THE PRIOR ART
The prior art in metal swimming pools has involved the use of sheet steel and sheet aluminum siding and extruded aluminum siding or walls. The prior art metal sheet siding, as applied to swimming pool construction, has been a continuous metal sheet wherein only a single joint was required. Joints of this type were at the seam where the metal sheet came to an end and overlapped itself and the sheet metal ends were secured together at the overlap. For this reason, the prior art swimming pools having sheet metal walls or siding, have been capable of taking or withstanding the hoop stresses themselves. On the other hand, the swimming pools formed from panels of extruded aluminum have been incapable of handling the hoop stresses at the joint securing adjacent panels together except in cases where the amount of aluminum used was excessively large in relation to the amount of water in the swimming pool and the forces applied by the water. For this reason, the prior art extruded aluminum swimming pools were economically incapable of competing with the sheet metal variety because the problem whereby the joint was incapable of handling the hoop stresses alone could be overcome only by the use of excessive metal, thereby driving up the cost. As an alternative, this problem was overcome by securing the panels in top and bottom rails (e.g. U.S. Pat. No. 3,736,599) or members which bore the load or hoop stresses from the water in the pool in a circular or other configuration, depending upon the configuration of the perimeter of the pool. These top and bottom rails also materially increased the cost of the pools made from extruded aluminum panels. However, it has been recognized that extruded aluminum walls have advantages over metal sheeting in that they are stiffer, have better aesthetic properties and, as compared with steel, are more corrosion resistant. It has therefore been a major objective in the arts to be able to produce an extruded aluminum panel swimming pool which is capable of competing with those formed from metal sheeting, not only on the basis of better stiffness and aesthetic properties, but also on the basis of economics.